Add structure to PDFs

When
you export to Adobe PDF with the Create Tagged PDF option selected
in the General area of the Export Adobe PDF dialog box, the exported
pages are automatically tagged with a set of structure tags that
describe the content, identifying page items such as headlines,
stories, and figures. To add additional tags or to fine-tune existing
ones before you export, you can use the Tags panel in InDesign.
The Structure pane (View > Structure > Show
Structure) reflects the changes.

You can improve the accessibility and reuse of Adobe PDF documents
by adding tags to the InDesign document before you export. If your
PDF documents don’t contain tags, Adobe Reader or Acrobat may attempt
to automatically tag the document when the user reads or reflows
it, but the results may be disappointing. If you do not get the
results you want in the exported PDF file, you can use tools in
Acrobat 6.0 Professional and later to edit the structure
of tagged PDF documents. For the most advanced tools, use Acrobat 9
Professional.

When you apply tags to a document for PDF export, the tags do
not control which content is exported to PDF, as is the case with
XML export. Instead, the tags give Acrobat more information about
the document’s structural contents.

Advantages of using tags

By applying tags
to your document before exporting to PDF, you can do the following:

Mark and hide printing artifacts, text, and images so that
they won’t appear when reflowed in Acrobat. For example, if you
tag a page item as Artifact, the page item will not be displayed
when you reflow the contents of a tagged Adobe PDF document on a
handheld device, a small display, or a monitor at a large magnification.

Add alternative text to figures so that the text can be read
aloud to the visually impaired with screen-reading software.

Replace graphic letters, such as ornate drop-caps, with readable
letters.

Provide a title for a set of articles, or group stories and
figures into articles.

Order stories and figures to establish a reading order.

Recognize tables, formatted lists, and tables of contents.
Recognize which content blocks belong to the different stories.

Include text formatting information such as Unicode values
of characters, spacing between words, and the recognition of soft
and hard hyphens.

How tags affect reuse and accessibility

The
content of an Adobe PDF document can be reused for other purposes.
For example, you might create an Adobe PDF file of a report with
text, tables, and images, and then use various formats to distribute
it: for printing or reading on a full-sized monitor, for viewing
on a handheld device, for reading out loud by a screen reader, and
for direct access through a web browser as HTML pages. The ease
and reliability with which you can reuse the content depends on
the underlying logical structure of the document.

To make sure that your Adobe PDF documents can be reused and
accessed reliably, you must add tags to them. Tagging adds an underlying
organizational structure, or logical structure tree,
to the document. The logical structure tree refers to the organization
of the document’s content, such as title page, chapters, sections,
and subsection. It can indicate the precise reading order and improve navigation—particularly
for longer, more complex documents—without changing the appearance
of the PDF document.

For people who are not able to see or decode the visual appearance
of documents, assistive technology can access the content of the
document reliably by using the logical structure tree. Most assistive
technology depends on this structure to convey the meaning of content
and images in an alternative format, such as sound. In an untagged
document, no such structure exists, and Acrobat must infer a structure
based on the reading order choices in the preferences. This method
is unreliable and often results in page items read in the wrong
order or not read at all.

The tags appear
on the Tags tab in Acrobat 6.0 and later, where they are
nested according to the relationship definitions for the tagged
elements. You cannot edit tags in Acrobat Standard. If your work
requires you to work directly with tags, you should upgrade to Acrobat 9
Professional. For more information, see Acrobat Help.

Logical structure tree on the Tags tab in Acrobat 9

Бележка:

Tags used in Adobe PDF files can be compared
to tags in HTML and XML files. To learn more about basic tagging
concepts, see any of the many references and text books available
in bookstores, in libraries, and on the Internet.

Understand and optimize reflow

You can reflow a PDF document
to read it on handheld devices, smaller displays, or standard monitors
at large magnifications, without having to scroll horizontally to
read each line.

When you reflow an Adobe PDF document, some content carries into
the reflowed document and some doesn’t. In most cases, only readable
text reflows into the reflowed document. Readable text includes
articles, paragraphs, tables, images, and formatted lists. Text
that doesn’t reflow includes forms, comments, digital signature
fields, and page artifacts, such as page numbers, headers, and footers.
Pages that contain both readable text and form or digital signature
fields don’t reflow. Vertical text reflows horizontally.

As an author, you can optimize your PDF documents for reflow
by tagging them. Tagging ensures that text blocks reflow and that
content follows the appropriate sequences, so readers can follow
a story that spans different pages and columns without other stories
interrupting the flow. The reading order is defined by the structure
tree, which you can change in the Structure pane.

Headings and columns (top) reflow in a logical reading order
(bottom).

Tag page items

You
can tag text frames and graphics automatically or manually. After
you tag page items, you can use the Structure pane to change the
order of your page by dragging elements to a new location within
the hierarchy. If you change the order of the elements in the Structure
pane, these changes are passed on to the Adobe PDF file. The order
of the elements becomes useful when the PDF file is saved from Acrobat
as an HTML or XML file. The order is also useful when you export
an InDesign document for Dreamweaver (XHTML) or Digital Editions (EPUB)
format.

Tag page items automatically

When you choose the Add Untagged Items command,
InDesign adds tags to the Tags panel, and applies the Story and
Figure tags to certain untagged page items. The Story tag is applied
to any untagged text frames, and the Figure tag is applied to any
untagged graphics. You can then manually apply other tags to sections
of text. However, automatically tagging page items does not guarantee that
the items will be structured accordingly in the exported PDF file.

Choose Window > Utilities > Tags
to display the Tags panel.

Choose View > Structure > Show
Structure to display the Structure pane, to the left of the Document
window.

Choose Add Untagged Items from the Structure pane menu.

Tags in the Structure pane and Tags panel

Tag page items manually

Choose Window > Utilities
> Tags to display the Tags panel.

Choose View > Structure > Show
Structure to display the Structure pane, to the left of the Document
window.

Choose Add Untagged Items from the Structure pane menu.

Select a page item in the document.

Select a tag in the Tags panel. Note the following suggested
uses for certain imported tags:

Artifact

The Artifact tag lets you hide page items, such as page
numbers or unimportant objects, when viewing the exported PDF file
in Reflow view, which displays only tagged items; see your Adobe
Acrobat documentation. This is especially useful for viewing PDF
files on a handheld device or in other PDF readers.

Cell

Use this tag for table cells.

Figure

Use this tag for placed graphics. The Figure tag is applied
to all untagged graphics placed in your document when you choose
Add Untagged Items.

Paragraph tags (P, H, H1–H6)

These tags have no effect on the exported PDF text when
viewed in Reflow view. However, they can be useful in some situations when
exporting a PDF file to HTML format.

Story structure tag (PDF)Story

Use this tag for stories. The Story tag is applied to
all untagged text frames when you choose Add Untagged Items. For
example, suppose you have an InDesign document formatted with three
paragraph styles: Head1, Head2, and Body. First, map these paragraph
styles to the H1, H2, and P tags, respectively. Next, export to
PDF. Finally, when you export the PDF document to HTML or XML in
Acrobat, the paragraphs tagged as H1, H2, and P will display appropriately (such
as with large bold letters in H1) in a web browser. For information
on exporting the PDF document to HTML or XML, see your
Adobe Acrobat documentation.

Label graphics for use with screen-reader
software

If you want screen readers to
describe graphical elements that illustrate important concepts in
the document, you must provide the description. Figures and multimedia
aren’t recognized or read by a screen reader unless you add alternate
text to the tag properties.

The Alt text attribute lets you
create alternate text that can be read in lieu of viewing an illustration.
ActualText is similar to Alt text in that it appears in lieu of an
image. The ActualText attribute lets you substitute an image that
is part of a word, such as when a fancy image is used for a drop
cap. In this example, the ActualText attribute allows the drop cap
letter to be read as part of the word.

When you export to
Adobe PDF, the Alt text and Actual Text attribute values are stored
in the PDF file and can be viewed in Acrobat 6.0 and later.
This alternate text information can then be used when the PDF file
is saved from Acrobat as an HTML or XML file. For more information,
see your Adobe Acrobat documentation.

To make sure the image is tagged as Figure, select the
image, and then select Figure in the Tags panel.

Select the Figure element in the Structure pane, and
then choose New Attribute from the Structure pane menu.

For Name, type either Alt or ActualText (this
feature is case-sensitive).

For Value, type the text that will appear instead of
the image.

Group page items into an Article
element

Use the Structure pane to logically group page items into an Article element. For example, if a set of stories spans multiple pages, you can create an umbrella element that will contain these stories in a single group. These umbrella elements are called structural elements. You can also name your grouped articles.

Бележка:

You cannot tag grouped page items.

To group page items, select New Element
from the Structure pane menu, select the Article element in the
Tags panel, and then drag page elements underneath it in the Structure
pane.

To name grouped items, right-click the Article element
in the Structure pane and choose New Attribute. For Name, type Title.
For Value, type the name of the article you want to use.